Bacterial Clearance Is Enhanced by α2,3- and α2,6-Sialyllactose via Receptor-Mediated Endocytosis and Phagocytosis

Jimin Kim, Yong-Jae Kim, Jae Wha Kim

Andreas J.Bäumler, Editor

Jimin Kim

Division of Systems Biology and Bioengineering, South Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of KoreaDepartment of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology, Daejeon, Republic of Korea

Division of Systems Biology and Bioengineering, South Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of KoreaDepartment of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology, Daejeon, Republic of Korea

ABSTRACT

Sialyllactose (SL) is a representative human milk oligosaccharide (HMO) of human breast milk. The roles of SL in infant brain development and immunity have been reported in previous studies. In this study, we identified the impact of SL on innate immunity. Our results showed that the administration of SL had significant efficacy on bacterial clearance in Pseudomonas aeruginosa K-infected mice. We also examined the role of SL in the human THP-1 macrophage-like cell line. SL effectively promoted receptor-mediated endocytosis and phagocytosis. Furthermore, SL accelerated the recruitment of Rac1 to the cell membrane, leading to the generation of reactive oxygen species for the elimination of phagocytosed bacteria. Our findings provide a new perspective on the role of SL in breast milk and suggest its application as a therapeutic agent to treat bacterial and viral infections.